Add initialization for structures

Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
diff --git a/tests/suites/test_suite_ecdh.function b/tests/suites/test_suite_ecdh.function
index f52e5b8..515a974 100644
--- a/tests/suites/test_suite_ecdh.function
+++ b/tests/suites/test_suite_ecdh.function
@@ -50,6 +50,7 @@
     mbedtls_ecp_keypair kp;
     int invalid_side = 42;
 
+    mbedtls_ecdh_init( &ctx );
     mbedtls_ecp_keypair_init( &kp );
 
     TEST_EQUAL( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,